KUALA LUMPUR, Feb 10 — A heterologous booster (Sinovac primary vaccination, followed by a Pfizer booster) offers greater protection against infection than a homologous booster dose (three doses of Sinovac) among Sinovac recipients, according to the Institute for Clinical Research (ICR), Ministry of Health (MOH).
While refuting the claims made by Pharmaniaga Berhad regarding the lower effectiveness of heterologous boosting for Sinovac primary vaccination recipients against Omicron, ICR noted that the prevailing facts and evidence were misrepresented.
“Globally, there is emerging and consistent evidence that heterologous booster vaccination results in more robust immune responses and is more effective than homologous boosting for recipients of primary series of inactivated vaccines (Sinovac).
“In line with emerging evidence and the ongoing Omicron wave, the MOH continues to recommend Pfizer or AstraZeneca as the preferred booster for Sinovac vaccine recipients,” ICR said in a statement today.
It said, in Malaysia, the Real-World Effectiveness of COVID-19 Vaccine under the Malaysian National COVID-19 Immunisation Programme study used data from Nov 21, 2021, until Jan 7, 2022, to compare the COVID-19 infection rates among recipients of booster doses and those who had only completed primary vaccination.
“The analysis is based on real-world data, which included 13 million people who had received Pfizer and Sinovac primary vaccination series.
“After accounting for confounders, those who have just received booster doses were at least 90 per cent less likely to be infected with COVID-19 than those with only two doses,” it said.
Citing a few studies conducted in various countries as examples, ICR explained further the effectiveness of heterologous boosting for Sinovac primary vaccination.
“In a study done in Hong Kong SAR, heterologous Pfizer booster following two doses of Sinovac improved neutralising antibody levels against Omicron variant at three to five weeks post-booster dose but three doses of Sinovac failed to elicit neutralising antibody responses to Omicron in most recipients.
“In another study conducted in Brazil, heterologous boosting (with AstraZeneca, Janssen, and Pfizer) resulted in more robust immune responses than homologous boosting with Sinovac booster, hence potentially stronger protection,” it said.
Meanwhile, it said in an interim statement on booster doses, the World Health Organisation (WHO) also remarked that both homologous and heterologous booster regimens are immunologically effective.
“A preprint from a study conducted in Chile observed an adjusted vaccine effectiveness against symptomatic COVID-19 of 78.8 per cent for three doses of Sinovac, 96.5 per cent for Pfizer booster (following two doses of Sinovac) and 93.2 per cent for AstraZeneca booster (following two doses of Sinovac).
Source: BERNAMA News Agency
